Background <p>Cell senescence-associated endothelia dysfunction is a vital point in the pathological progression of atherosclerosis (AS). G-protein coupled receptor 4 (GPR4) is a proton-sensing receptor involved in developing endothelial dysfunction.</p> Objective <p>In this study, we investigated the protective role of NE 52-QQ57, a GPR4 inhibitor in endothelial cell senescence induced using an oxidized low-density lipoprotein (ox-LDL). We also unravel the underlying molecular mechanism of NE 52-QQ57 as a therapeutic agent.</p> Methods <p>Endothelial cell senescence model was established using human aortic endothelial cells (HAECs) stimulated with ox-LDL. The expression levels of GPR4, p53, p16, and sirtuin1 (SIRT1) were evaluated using real-time PCR and western blot assays. ROS production was determined using dihydroethidium (DHE) staining. Further, interleukin-6 (IL-6) and monocyte chemotactic protein 1 (MCP-1) secretion and expression were determined using ELISA and real-time PCR analysis, respectively. Finally, β-galactosidase (SA-β-Gal) staining associated with cell senescence, telomerase activity, and cell cycle assay were used to determine the state of cell senescence.</p> Results <p>Firstly, GPR4 was found to be upregulated in the ox-LDL-stimulated HAECs. We also identified elevated ROS, IL-6, and MCP-1 levels induced by ox-LDL and significantly abrogated by NE 52-QQ57 treatment. Second, a reversal in SA-β-Gal activity, telomerase activity, and G0/G1 proportion, with an upregulation in p53 and p16 expressions was observed on NE 52-QQ57 treatment in the ox-LDL induced model. Lastly, the decreased expression level of SIRT1 was extremely elevated by NE 52-QQ57. Notably, the inhibitory effect of NE 52-QQ57 against ox-LDL-induced cell senescence was abolished by the SIRT1 inhibitor EX-527.</p> Conclusion <p>The GPR4 antagonist NE 52-QQ57 might prevent cellular senescence by promoting the expression of SIRT1.</p>